Moving robot and controlling method thereof

ABSTRACT

A moving robot includes a traveling unit, a power supply unit, a communication unit, and a memory to store therein coordinates information regarding a point to which the main body has moved by a reference distance in a state of being in contact with the charging station, and a control unit to output a control command to return to the charging station based on a state of the power supply unit while the main body travels in the one area, to determine a position of the charging station from a current position of the main body based on a first signal transmitted from the charging station and a second signal transmitted by the communication unit, in response to the output of the control command, and to controls the traveling unit so that the main body moves to a position corresponding to the stored coordinates information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2019/009257, filed on Jul. 25, 2019, which claims the benefit of earlier filing date and rights of priority to U.S Provisional application No. 62/714,088 filed on Aug. 3, 2018 and Korean Application No. 10-2019-0050966 filed on Apr. 30, 2019, the contents of which are all hereby incorporated by reference herein in their entirety.

BACKGROUND Technical Field

The present disclosure relates to a moving robot that autonomously travels in a designated area, and a method for controlling the same.

Background Art

Generally, a moving robot is a device that automatically performs a predetermined operation while traveling by itself in a predetermined range without a user's operation. The moving robot senses obstacles located in the area and performs its operations by moving close to or away from such obstacles.

Such a moving robot may include a cleaning robot that carries out cleaning while traveling in an area, as well as a lawn mower robot that mows the grass on a bottom of the area.

Generally, lawn mowers include a passenger type which a user boards and controls to mow the lawn or cut the grass during movement, and a work-behind type or hand-operating type that is pulled or pushed manually by a user to cut the grass. Such lawn mowers are moved by a direct control of the user to mow the lawn, which causes user's inconvenience in that the device is operated only directly by the user.

Accordingly, a moving robot type lawn mower that an element for mowing the lawn is provided on a moving robot, namely, a lawn mower robot has been studied. However, since the lawn mower robot operates outdoors other than indoors, it is necessary to set an area to be moved in advance. Specifically, since the outdoors is an open space unlike the indoors, an area designation should first be carried out, and an area to be driven by the robot should be limited to a space where grass is growing.

For this purpose, in Korean Patent Laid-Open Publication No. 2015-0125508, wires are laid under the ground where grass is planted, in order to set an area to be moved by a lawn mower robot or a moving robot, and the moving robot is controlled to move in an inner area of the wires. Then, a boundary for the moving robot is set based on a voltage value induced by the wires.

However, this method has a problem that the wires must be laid under the ground every time of setting the boundary. In addition, in order to change the boundary once set, new wires must be laid after the previously laid wires are removed, which causes much time and efforts for the boundary setting.

The US Patent laid-open Publication No. US 2017/0026818 discloses a method in which a distance between Beacon and the mobile lawn mower robot is determined by pairing the mobile lawn mower robot and the Beacon, whether the Beacon is located within a pairing distance is determined by comparing the determined distance with the pairing distance, and the result of the determination is used for a navigator.

Recently, a method of controlling the travel of a moving robot by using a low-cost Ultra-wideband (UWB) communication technology known to have precision of about 30 cm or shorter has been studied. UWB is suitable for real-time location tracking because it is hardly affected by multipath problems by virtue of its properties of precise region estimation and material penetration.

By using such UWB communication technology, a relative location of another device, for example, UWB tag, existing in a UWB positioning range may be calculated. In the case of determining the relative location of the UWB tag using the UWB communication technology, Angle of Arrival (AoA) positioning may be used.

On the other hand, since the moving robot travels using a rechargeable battery, recharging must be performed according to the remaining power level of the battery. Accordingly, researches and commercialization are carried out for charging a moving robot by making the moving robot go to a charging station, which is installed in advance for the moving robot, by itself according to its battery state. However, in outdoor environments, it is not easy for the moving robot to accurately return to the charging station due to a widely open space and various terrain characteristics.

Even if the moving robot reaches the position of the charging station, it is necessary to set an accurate docking path in order to correctly connect its connector to a connector of the charging station. When wires are laid in a boundary of an area where the moving robot travels, the moving robot moves to the charging station along the laid wires, but laying the wires in the boundary causes various other problems.

Korean Patent Registration No. 10-0902115 proposes a method of precisely guiding a moving robot to a charging station using a camera and infrared sensors. However, in the case of the camera and the infrared sensors, the docking position can be precisely guided only when the moving robot approaches the charging station to some extent. Therefore, there are various problems in guiding a docking path to the charging station for the moving robot in a widely open space such as outdoor environments. Also, as in the case where the moving robot is moving toward the charging station from the rear with respect to a docking direction of the charging station, if the moving robot is located in a blind spot of signals (or an angle of view), a docking position is less likely to be induced.

SUMMARY Technical Problem

Therefore, one aspect of the present disclosure is to provide a moving robot, capable of carrying out docking for charging by accurately returning to a charging station from a current position even without installing wires in a travel boundary of the moving robot, and a method of controlling the same.

Another aspect of the present disclosure is to provide a moving robot, capable of efficiently setting a docking path for charging using UWB signals without having to lay even a guide wire around a charging station, and a method of controlling the same.

Still another aspect of the present disclosure is to provide a moving robot, capable of accurately carrying out docking even without using a magnetic field SLAM while minimizing a signal blind spot by covering all the 360-degree directions when the moving robot attempts to dock to a charging station, and a method of controlling the same.

Technical Solution

To achieve those aspects and other advantages of the present disclosure, there is provided a moving robot that travels within one area where a charging station is installed, the moving robot including a traveling unit to rotate or move a main body, a power supply unit to supply power to the main body, a communication unit to transmit and receive signals to and from the charging station, a memory to store therein coordinates information regarding a point to which the main body has moved by a reference distance in a state of being in contact with the charging station, and a control unit to output a control command to return to the charging station based on a state of the power supply unit while the main body travels in the one area. In addition, the control unit may determine a position of the charging station from a current position of the main body based on a first signal transmitted from the charging station and a second signal transmitted by the communication unit, in response to the output of the control command, control the traveling unit so that the main body moves to a position corresponding to the stored coordinates information, calculate a rotation angle for docking to the charging station based on the first signal and the second signal when the main body reaches the position corresponding to the stored coordinates information, and control the traveling unit so that a head of the main body is rotated according to the calculated rotation angle.

In one embodiment, the charging station may be provided with a pair of Ultra-wideband (UWB) modules to transmit the first signal and receive the second signal, and the communication unit of the main body may be provided with a pair of UWB modules to receive the first signal and transmit the second signal.

In one embodiment, the pair of UWB modules provided in the communication unit may be disposed to be symmetric in right and left directions with respect to the front of the main body, and determine the position of the charging station with respect to the current position of the main body by receiving the first signal from the charging station, respectively.

In one embodiment, while the main body moves to the position corresponding to the stored coordinates information, the control unit may determine one intersection close to a head direction of the main body as the position of the charging station, of two intersections between a first circle that a distance between a first UWB anchor provided in the communication unit and a first UWB tag of the charging station is a radius and the first UWB anchor is a center, and a second circle that a distance between a second UWB anchor provided in the communication unit and a second UWB tag of the charging station is a radius and the second UWB anchor is a center.

In one embodiment, coordinates information of a point to which the main body has moved backward by a reference distance in a state of being in contact with the charging station may include angle information calculated based on the first signal and the second signal.

In one embodiment, the control unit may calculate distance information and angle information between the current position of the main body and the charging station based on the first signal received from the charging station and the second signal transmitted by the communication unit, in response to the output of the control command, and control the traveling unit so that the head of the main body is rotated toward the position corresponding to the stored coordinates information.

In one embodiment, the control unit may check the position of the charging station in real time based on the first signal received through a plurality of UWB modules while the main body moves to the position corresponding to the stored coordinates information after the head of the main body is rotated toward the point corresponding to the stored coordinates information.

In one embodiment, after the main body moves to the position corresponding to the stored coordinates information, the control unit may determine a head direction of the main body on the basis of the angle information calculated based on the first signal received from the charging station and the second signal transmitted by the communication unit, and then control the traveling unit so that the head is rotated according to the determined head direction.

In one embodiment, after the head is rotated according to the determined head direction, the control unit may check whether or not to correct the determined head direction, based on a difference between distances at which the first signal transmitted from the charging station is received by a first UWB module and a second UWB module disposed in the main body, respectively.

In one embodiment, a current head direction may be determined as a docking direction when it is determined that the distance at which the first signal is received by the first UWB module is the same as the distance at which the first signal is received by the second UWB module.

In one embodiment, the control unit may control the traveling unit so that the main body docks to the charging station by moving straightly by the reference distance, after the main body rotates the head according to the calculated rotation angle at the position corresponding to the stored coordinates information.

In one embodiment, the control unit may determine the position of the charging station in real time based on the first signal and the second signal while the main body moves to the position corresponding to the stored coordinates information, and set a docking path by avoiding the charging station when the position of the charging station is included in a path along which the main body moves to the stored coordinates information.

In one embodiment, the control unit may store position information regarding the main body at a time point when the control command has been output, and control the traveling unit so that the main body moves to the stored position information when the main body docks to the charging station and charging of the power supply unit is completed.

To achieve these aspects and other advantages according to the present disclosure, there is provided a method for controlling a moving robot that travels within one area where a charging station is installed, the method including storing in advance coordinates information regarding a point, to which a main body of the moving robot has moved by a reference distance in a state of being in contact with the charging station, outputting a control command to return to the charging station based on a state of a power supply unit that supplies power to the main body while the main body travels in the one area, determining a position of the charging station with respect to the main body based on a first signal transmitted from the charging station and a second signal transmitted by the main body, in response to the output of the control command, and controlling the main body to move to a position corresponding to the stored coordinates information, and calculating a rotation angle for docking to the charging station based on the first signal and the second signal when the main body reaches the position corresponding to the stored coordinates information, and controlling a head of the main body to be rotated according to the calculated rotation angle.

In one embodiment, the controlling the main body to move to the position corresponding to the stored coordinates information may include calculating distance information and angle information between a current position of the main body and the charging station based on the first signal received from the charging station and the second signal transmitted by the main body, in response to the output of the control command, and controlling the head of the main body to be rotated toward the position corresponding to the stored coordinates information.

In one embodiment, the method may further include checking the position of the charging station in real time based on the first signal received through a plurality of UWB modules provided in the main body while the main body moves to the position corresponding to the stored coordinates information after the head of the main body is rotated toward the position corresponding to the stored coordinates information.

In one embodiment, the method may further include, after the main body moves to the position corresponding to the stored coordinates information, determining a head direction of the main body on the basis of angle information calculated based on the first signal received from the charging station and the second signal transmitted by the main body, and rotating the head according to the determined head direction and docking to the charging station.

Advantageous Effects

As described above, in a moving robot and a control method thereof in accordance with an embodiment of the present disclosure, a docking path for charging can be set without having to set wires in a boundary along which the moving robot travels or to lay a guide wire under the ground around a charging station. In addition, since the moving robot can cover all the 360-degree directions when docking to the charging station even if it is located at anywhere within a boundary, a signal blind spot can be minimized and accurate docking can be carried out without using a magnetic field SLAM.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of a moving robot according to the present disclosure.

FIG. 2A is a conceptual view illustrating a state where the moving robot according to the present disclosure performs communications with a terminal, a charging station, and a server.

FIG. 2B is a block diagram illustrating an exemplary configuration of a moving robot according to the present disclosure, FIG. 2C is a block diagram illustrating an exemplary configuration of a terminal communicating with the moving robot according to the present disclosure, FIG. 2D is a block diagram illustrating an exemplary configuration of a charging station communicating with the moving robot according to the present disclosure.

FIG. 3 is a conceptual view illustrating a signal flow generated during communication among a moving robot, a terminal, a charging station, a location information transmitter, and GPS, in accordance with an embodiment of the present disclosure.

FIGS. 4A, 4B and 4C are conceptual views related to setting a virtual boundary for the moving robot without laying wires under the ground, in accordance with an embodiment of the present disclosure.

FIG. 5 is a view illustrating the concept of Angle of Arrival (AoA) positioning technology.

FIG. 6A is a view illustrating a concept of recognizing a position of a charging station according to the positioning technology of FIG. 5, and FIGS. 6B and 6C are exemplary views illustrating that the moving robot docks to the charging station using a guide wire.

FIG. 7 is a flowchart illustrating a method of controlling a moving robot in accordance with an embodiment of the present disclosure.

FIGS. 8A, 8B, 8C, 8D, 8E and 8F are conceptual views illustrating operations of FIG. 7 in detail.

FIG. 9 is a conceptual view illustrating a method of docking to the charging station when the moving robot is located in the existing blind spot in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, a moving robot according to the present disclosure will be described in detail with reference to the accompanying drawings.

Hereinafter, description will be given in detail of embodiments disclosed herein. Technical terms used in this specification are merely used for explaining specific embodiments, and should not be constructed to limit the scope of the technology disclosed herein.

First, the term “moving robot” disclosed herein may be used as the same meaning as “robot” which can autonomously travel, “lawn mower moving robot,” “lawn mower robot,” “lawn mower,” and “moving robot for mowing lawn,” and those terms will be used equally.

FIG. 1 is a block diagram of a moving robot for mowing lawn according to the present disclosure.

A moving robot according to the present disclosure may include an outer cover 101, an inner body (not shown), and wheels 1092.

The outer cover 101 may define appearance of the moving robot. The appearance of the moving robot may be formed in a shape similar to an automobile, for example. The outer cover 101 may be formed to cover an outside of the inner body (not shown).

The outer cover 101 may be mounted on an upper portion of the inner body so as to cover the upper portion of the inner body. A receiving portion may be formed inside the outer cover 101, and the inner body may be received in the receiving portion.

A bumper 102 may be provided on a front portion of the outer cover 101 in preparation for collision with an obstacle. The bumper 102 may be formed of a rubber material that can mitigate impact.

A plurality of ultrasonic sensor modules 103 may be mounted on a front upper portion of the outer cover 101. The plurality of ultrasonic sensor modules 103 is configured to emit ultrasonic waves toward the front of the robot while the robot travels, and receive reflected waves reflected from the obstacle, so as to detect the front obstacle.

The plurality of ultrasonic sensor modules 103 may be spaced apart from one another in a vehicle width direction. The plurality of ultrasonic sensor modules 103 may be spaced apart from the bumper 102 rearward by a designated distance. In addition, the plurality of ultrasonic sensor modules 103 may be replaced with other signal-based sensors, such as UWB sensors, other than the ultrasonic sensors.

The moving robot may include a control unit. The control unit may stop the operation of the moving robot when an obstacle is detected by receiving a detection signal from the ultrasonic sensor modules 103.

A first top cover 105 and a second top cover 106 may be provided on the top of the outer cover 101. A stop switch 107 may be provided between the first top cover 105 and the second top cover 106. The stop switch 107 may be mounted on the outer cover 101 to be pressed. When the user presses the stop switch 107 one time in an emergency state, the stop switch 107 may be switched on so that the operation of the moving robot is stopped. When the stop switch 107 is pressed once more, the operation of the moving robot may be restarted.

The plurality of wheels 1092 may be connected respectively to driving motors provided in the inner body, and rotatably mounted on both side surfaces of the inner body 160 in a widthwise direction of the inner body 160. Each of the plurality of wheels 1092 may be connected to the driving motors by a driving shaft, so as to be rotatable by receiving power from the driving motors.

The plurality of wheels 1092 may supply power for the travel of the robot, and each of the plurality of wheels 1092 may be controlled by the control unit independently to be rotated by different RPM.

In addition, a handle 120 (which may also be referred to as a ‘carrying handle’) may be installed on the outer cover 101 so that the user can grip it with a hand while carrying the moving robot.

FIG. 2A illustrates a state in which the moving robot 100, the charging station 300, the terminal 200, and the server 500 perform communication, in accordance with the present disclosure.

The moving robot 100 according to the present disclosure may exchange data with the charging station 300 or the terminal 200 through network communication.

In addition, the moving robot 100 may perform a weeding-related operation or a corresponding operation according to a control command received from the charging station 300 or the terminal 200 through network communication or other communication. The charging station 300 according to the present disclosure may exchange data with the terminal 200 through network communication.

Here, the network communication may refer to at least one of wireless communication technologies, such as a wireless LAN (WLAN), a wireless personal area network (WPAN), a wireless fidelity (Wi-Fi) Wi-Fi direct, Digital Living Network Alliance (DLNA), Wireless Broadband (WiBro), World Interoperability for Microwave Access (WiMAX), Zigbee, Z-wave, Blue-Tooth, Radio Frequency Identification (RFID), Infrared Data Association (IrDA), Ultrawide-Band (UWB), Wireless Universal Serial Bus (USB), and the like.

Here, other communications may refer to wireless communication technologies by which communications are performed directly without moving communication networks between the moving robot 100 and the charging station 300, between the moving robot 100 and the terminal 200, and between the charging station 300 and the terminal 200.

The illustrated network communication may vary depending on a communication method of the moving robot 100.

In FIG. 2A, the moving robot 100 may provide information sensed through each sensing unit to the charging station 300 or the terminal 200 through network communication. In addition, the terminal 200 may transmit a control command generated based on the received information to the moving robot 100 through the network communication.

On the other hand, the terminal 200 may be named as a controller, a remote controller, or the like, which is operated by a user to control operations related to the travel of the moving robot 100. To this end, the terminal 200 may be provided with an application installed therein for controlling operations related to the traveling of the moving robot 100, and the corresponding application may be executed through a user operation.

In FIG. 2A, a communication unit of the moving robot 100 and a communication unit of the terminal 200 may also directly communicate with each other or indirectly communicate with each other via another router (not shown), to recognize information related to a traveling operation of the moving robot and locations of the moving robot and the terminal.

Also, the moving robot 100, the charging station 300, the terminal 200 and the server 500 may be connected via a network and exchange data with one another.

For example, the server 500 may exchange data with the moving robot 100 and/or the terminal 200, to register information related to a boundary set for the moving robot 100, map information based on the set boundary, obstacle information on the map. In addition, the server 500 may provide the registered information to the moving robot 100, the charging station 300, and/or the terminal 200 according to a request.

The server 500 may be wirelessly connected to the moving robot 100 through the terminal 200. Alternatively, the server 500 may be connected to the moving robot 100 without passing through the terminal 200.

The server 500 may include a programmable processor and may include various algorithms. By way of example, the server 500 may be provided with algorithms related to performing machine learning and/or data mining. As an example, the server 500 may include a speech recognition algorithm. In this case, when receiving voice data, the received voice data may be output by being converted into data in a text format.

Meanwhile, the server 500 may store firmware information and driving information (course information, and the like) for the moving robot 100, and register product information related to the moving robot 100. For example, the server 300 may be a server managed by a moving robot manufacturer or a server managed by an open application store operator.

Hereinafter, FIG. 2B is a block diagram illustrating an exemplary configuration of the moving robot 100 according to the present disclosure, and FIG. 2C is a block diagram illustrating an exemplary configuration of the terminal 200 communicating with the moving robot 100.

First, the configuration of the moving robot 100 will be described in detail with reference to FIG. 2B.

As illustrated in FIG. 2B, the moving robot 100 may include a communication unit 1100, an input unit 1200, a traveling unit 1300, a sensing unit 1400 provided with a location detector 1401 and an obstacle detector 1402, an output unit 1500, a memory 1600, a weeding unit 1700, a control unit 1800, and a power supply unit 1900.

The communication unit 1100 may perform communication with the terminal 200 through a wireless communication scheme. Also, the communication unit 1100 may perform communication with the terminal which is connected to a predetermined network to control an external server or the moving robot.

The communication unit 1100 may transmit information related to a generated map to the terminal 200. The communication unit 1100 may receive a command from the terminal 200 and transmit data regarding an operation state of the moving robot 100 to the terminal 200.

The communication unit 1100 transmits and receives data by being equipped with a communication module such as Wi-Fi, WiBro, and the like, as well as through short-range wireless communications such as Zigbee and Bluetooth. In addition, the communication unit 1100 may include a UWB module for transmitting an UWB signal.

The input unit 1200 may include an input element such as at least one button, a switch, and a touch pad. The output unit 1500 may include an output element such as a display unit and a speaker. When the output unit 1500 is used simultaneously as the input element and the output element, a user command can be input and the operation state of the moving robot can be output through the display unit or the speaker.

The memory 1600 may store therein an input detection signal, reference data for determining an obstacle, and obstacle information regarding a detected obstacle. The memory 1600 may also store therein control data for controlling the operation of the moving robot and data according to a cleaning mode of the moving robot.

The memory 1600 may store therein collected location information, and information related to a travel area and its boundary. For example, the memory 1600 may store data that is readable by a microprocessor, and may be one of a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), ROM, RAM, CD-ROM, a magnetic tape, a floppy disk, or an optical data storage device.

The traveling unit 1300 may include at least one driving motor, and may allow the moving robot to move according to a control command of the control unit 1800. The traveling unit 1300 may include a left wheel driving motor for rotating the left wheel and a right wheel driving motor for rotating the right wheel. In addition, the traveling unit 1300 may further include one or more auxiliary wheels for stable support.

For example, while the moving robot main body travels, the left wheel driving motor and the right wheel driving motor may be rotated in the same direction. A traveling direction of the moving robot main body (or moving robot) 100 may be switched when the left wheel driving motor and the right wheel driving motor are rotated at different speeds or in opposite directions.

The weeding unit 1700 cuts the lawn on a bottom surface while the moving robot is traveling. The weeding unit 1700 is provided with a brush or blade for cutting the lawn, and cuts the lawn on the bottom surface in a rotating manner.

The obstacle detector 1402 may include a plurality of sensors for detecting obstacles existing in front of the moving robot. The obstacle detector 1402 may detect obstacles in front of the main body, namely, in the traveling direction of the moving robot, using at least one of a laser, ultrasonic waves, infrared rays, and a 3D sensor.

In addition, the obstacle detector 1402 may include a camera for capturing the front of the moving robot so as to detect an obstacle. The camera is a digital camera, which may include an image sensor (not shown) and an image processor (not shown). An image sensor is an apparatus for converting an optical image into an electrical signal. The image sensor is configured as a chip on which a plurality of photo diodes is integrated, and the photodiode may be a pixel, for example. Electric charges are accumulated in the respective pixels by an image, which is formed on the chip by light passing through a lens, and the electric charges accumulated in the pixels are converted into an electrical signal (for example, voltage). Charge Coupled Device (CCD), Complementary Metal Oxide Semiconductor (CMOS), and the like are well known as image sensors. In addition, a DSP or the like may be provided as the image processor.

The location detector 1401 includes a plurality of sensor modules for transmitting and receiving location information. The location detector 1401 includes a GPS module that transmits and receives GPS signals or a location sensor module that transmits and receives location information to and from a location information transmitter 50 (see FIG. 3). For example, the location detector 140 is provided with a sensor module that transmits and receives an ultrasonic, UWB, or infrared signal when the location information transmitter transmits a signal through one of ultrasonic wave, ultra-wideband (UWB), and infrared ray.

When the location sensor module is implemented as a UWB sensor module, even if an obstacle exists between the location information transmitter 50 and the moving robot 100, signals can be transmitted and received through such an obstacle or the like. Therefore, transmission and reception of the UWB signals are smoothly carried out.

Unless otherwise mentioned, it may be premised that the location information transmitter 50 and the moving robot 100, the location information transmitter 50 and the terminal 200, and the moving robot 100 and the terminal 200 are provided with at least one UWB sensor module so as to transmit and receive the UWB signals to and from each other.

Also, even when the moving robot 100 moves while following the terminal 200, the location may be determined using the sensor module.

For example, when the moving robot 100 travels while following the terminal 200, the terminal and the moving robot each include a UWB sensor and perform wireless communication with each other. The terminal may transmit a signal from its UWB sensor. The moving robot may receive the signal of the terminal through its UWB sensor and determine the location of the terminal based on the signal of the terminal so as to follow the terminal.

As described above, since the UWB signal transmitted by the UWB sensor can pass through an obstacle, the signal transmission is not affected even if the user moves while holding the terminal. However, in the case of an obstacle having a designated size or more, the signal transmission may be failed or a signal transmission distance may be reduced even if the signal is transmitted through the obstacle.

In addition, the UWB sensors provided in the terminal and the moving robot, respectively, may estimate or measure a distance between them. When the moving robot follows the terminal, the travel of the moving robot is controlled according to a distance from the terminal, so that the moving robot does not move away from the terminal by a predetermined distance. That is, the moving robot may follow the terminal while maintaining a proper distance so that the distance from the terminal is not too close or too far away.

The location detector 1401 may include one UWB sensor or a plurality of UWB sensors. For example, when the location detector 1401 includes two UWB sensors, for example, the two UWB sensors may be provided on left and right sides of the main body of the moving robot, respectively, to receive signals. Accordingly, the location detector 1401 may detect the location by comparing the received signals.

For example, when the distances measured respectively by the left sensor and the right sensor are different according to the locations of the moving robot and the terminal, relative locations of the moving robot and the terminal and a direction of the moving robot may be determined based on the distances.

Meanwhile, in addition to the obstacle detector 1402 and the location detector 1401, the sensing unit 1400 may include various sensors, such as a cliff detection sensor installed on a rear surface of the main body to detect a cliff, a rain sensor to detect a humid or rainy weather condition, a proximity sensor, a touch sensor, an RGB sensor, a fuel gauge sensor, an acceleration sensor, a geomagnetic sensor, a gravity sensor, a gyroscope sensor, an illuminance sensor, an environmental sensor (a thermometer, a radiation detection sensor, a heat detection sensor, a gas detection sensor, etc.), a plurality of 360-degree sensors, a floor state detection sensor, and the like.

In addition, the sensing unit 1400 may include at least one tilt sensor (not shown) for detecting movement of the main body. The tilt sensor calculates a tilted direction and a tilted angle of the main body when the main body is tilted in a front, rear, left, or right direction. The tilt sensor may be an acceleration sensor, or the like. In the case of the acceleration sensor, any of a gyro type, an inertial type, and a silicon semiconductor type is applicable. In addition, various sensors or devices capable of detecting the movement of the main body may be used.

The control unit 1800 controls data input/output, and controls the traveling unit 1300 so that the moving robot travels according to settings. The control unit 1800 controls the traveling unit 1300 to independently control the operations of the left wheel driving motor and the right wheel driving motor, so that the main body of the moving robot 100 travels straight or rotate.

The control unit 1800 determines a traveling direction corresponding to a signal received through the sensing unit 1400 and controls the traveling unit 1300. In addition, the control unit 1800 controls the traveling unit 1300 to vary a traveling speed, so that the moving robot travels or stops according to the distance from the terminal. Accordingly, the moving robot can move while following locations of the terminal corresponding to the changes in location of the terminal.

In addition, the control unit 1800 may control the moving robot to move, following the terminal 200, according to a set mode.

The control unit 1800 may set a virtual boundary for an area based on location information received from the terminal 200 or location information calculated through the location detector 1401. Also, the control unit 1800 may set any one of areas formed by set boundaries as a travel area. The control unit 1800 sets a boundary in a shape of a closed loop by connecting discontinuous location information with lines or curves, and sets an inner area of the set boundary as the travel area. Also, when a plurality of boundaries is set, the control unit 1800 may set any of areas formed by the plurality of boundaries as a travel area.

When the boundary and the travel area are set, the control unit 1800 controls the traveling unit 1300 so that the moving robot travels within the travel area without moving over the set boundary. The control unit 1800 calculates a current location based on received location information, and controls the traveling unit 1300 so that the calculated current location is located within the travel area set by the boundary.

In addition, the control unit 1800 may determine obstacle information input by the obstacle detector 1402 and travel avoiding obstacles. Also, the control unit 1800 may modify a preset travel area, if necessary, based on the obstacle information.

For example, the control unit 1800 may control the traveling unit 1300 to travel by passing through an obstacle or avoiding the obstacle, by way of changing a moving direction or a travel path in correspondence with obstacle information input from the obstacle detector.

The control unit 1800 may set the moving robot so as not to approach a cliff by a predetermined distance or closer when the cliff is detected. In addition, the control unit 1800 may change a traveling direction according to a user selection, which is input through the terminal 200, by way of transmitting traveling information regarding a detected obstacle to the terminal 200 and displaying such information on the terminal.

The power supply unit 1900 includes a rechargeable battery (or battery module) (not shown). The battery may be detachably mounted to the moving robot 100. When it is detected through the sensing unit 1400 that the battery gauge is insufficient, the control unit 1800 may control the traveling unit 1300 to move the moving robot to the location of a charging station for recharging the battery. When presence of the charging station is detected by the sensing unit 1400, recharging of the battery is performed.

Hereinafter, the main configuration of the terminal 200 that performs communication with the moving robot 100 according to the present disclosure will be described, with reference to FIG. 2C.

Referring to FIG. 2C, the terminal 200 may include a mobile terminal that can be carried by a user and may include a communication unit 210, an input unit 220, a UWB module 230, a sensing unit 240, a display unit 251, a memory 260, and a control unit 280.

The communication unit 210 may perform communication with an external server or the moving robot 100 through wireless communication. The communication unit 210 transmits and receives data by being equipped with a communication module such as Wi-Fi, WiBro, and the like, as well as through short-range wireless communications such as Zigbee and Bluetooth. In addition, the communication unit 210 may include a UWB module for transmitting a UWB signal.

The input unit 220 may include an input element such as at least one button, a switch, and a touch pad.

Also, the input unit 220 is configured to permit various types of inputs to the wearable device 100. Examples of such inputs include image information (or signal), audio information (or signal), data or various information input by a user, and may be provided with one or a plurality of cameras 221.

Such cameras 221 may process image frames of still pictures or videos obtained by image sensors in an image capture mode. The processed image frames may be displayed on the display unit 251 or stored in memory 170. Meanwhile, the cameras 221 provided in the terminal 200 may be arranged in a matrix configuration to permit a plurality of images having various angles or focal points to be input to the terminal 200. Also, the cameras 221 may be located in a stereoscopic arrangement to acquire left and right images for implementing a stereoscopic image.

The camera 221 typically includes at least one a camera sensor (CCD, CMOS, etc.), a photo sensor (or image sensors), and a laser sensor.

Implementing the camera 221 with a laser sensor may allow detection of a touch of a physical object with respect to a 3D stereoscopic image. The photo sensor may be laminated on, or overlapped with, the display device. The photo sensor may be configured to scan movement of the physical object in proximity to the touch screen. In more detail, the photo sensor may include photo diodes and transistors (TRs) at rows and columns to scan content received at the photo sensor using an electrical signal which changes according to the quantity of applied light. Namely, the photo sensor may calculate the coordinates of the physical object according to variation of light to thus obtain location information of the physical object.

The display unit 251 may include a touch sensor to receive a control command through a touch input. In addition, the display unit 251 may be configured to output a control screen for controlling the moving robot 100, and a map screen on which a set boundary and the location of the moving robot 100 are displayed.

The memory 260 may store therein data related to the travel of the moving robot 100. In addition, the memory 260 may store therein location information regarding the moving robot 100 and the terminal 200, and information regarding a travel area of the moving robot and a boundary of the travel area. For example, the memory 1600 may store data that is readable by a microprocessor, and may be one of a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), ROM, RAM, CD-ROM, a magnetic tape, a floppy disk, or an optical data storage device.

The sensing unit 240 includes a location detector (not shown) for transmitting and receiving location information, and at least some of a gyro sensor and an acceleration sensor for sensing a change in spatial motion of the terminal 200, a geomagnetic sensor, and an IMU (Inertia Measurement Unit) sensor. At this time, the gyro sensor and the acceleration sensor may be implemented as any one of 3-axis, 6-axis, or 9-axis gyro sensor and acceleration sensor.

The location detector includes a plurality of sensor modules for transmitting and receiving location information. For example, the location detector may include a GPS module, an Ultra-Wideband (UWB) module, a geomagnetic sensor, an acceleration sensor, a gyro sensor, and the like, to recognize coordinates of a point which is indicated by a posture change such as a tilt or the like, as well as a current location of the terminal 200.

The UWB module 230 which is included in the location detector or separately provided may exchange UWB signals with the moving robot 100 and/or the location information transmitter 50. Accordingly, not only the location of the terminal 200 but also the location of the moving robot 100 with respect to the terminal 200, the location of the location information transmitter 50 with respect to the terminal 200, the location of the location information transmitter 50 with respect to the moving robot 100, and the like can be recognized.

The acceleration sensor is a sensor that measures how much force an object is receiving based on gravitational acceleration of the earth. A three-axis acceleration sensor refers to a sensor capable of measuring magnitude of acceleration in x, y, and z-axial directions. Such an acceleration sensor may be used as one three-axis acceleration sensor, a six-axis acceleration sensor with two three-axis acceleration sensors applied, or a nine-axis acceleration sensor with three three-axis acceleration sensors applied.

By using a sensing value of the three-axis acceleration sensor, roll (rotation with respect to the x axis) and pitch (rotation with respect to the y axis) may be calculated. A unit used is [g]. On the other hand, rotation with respect to the z axis coinciding with the direction of gravitational acceleration, that is, a yaw (rotation with respect to the z axis) value may be calculated only by additionally applying a three-axis gyro sensor or a magnetometer. Also, in a motion state in which an object is not stopped, a tilt value cannot be detected by only the three-axis acceleration sensor.

The three-axis gyro sensor is a sensor for controlling posture of an object, namely, a sensor capable of measuring angular velocity in the x, y, and z-axial directions. Here, the angular velocity refers to an angle of rotation per hour. A unit used is [degree/sec].

The IMU sensor is a combined sensor of a three-axis acceleration sensor and a three-axis gyro sensor. Alternatively, the IMU sensor is a nine-axis sensor with a three-axis acceleration sensor, a three-axis gyro sensor, and a three-axis geomagnetic sensor. By using such an IMU sensor, the roll, the pitch and the yaw can all be calculated.

The UWB module 230 may transmit or receive a UWB signal through a UWB module provided in the moving robot 100. The terminal 200 may play a role of ‘remote control device’ in that it can control the travel or weeding operation of the moving robot 100 through communication with the moving robot 100.

In addition to the UWB module 210, the terminal 200 may further include a distance measuring sensor.

The distance measuring sensor may emit at least one of a laser light signal, an IR signal, an ultrasonic signal, a carrier frequency, and an impulse signal, and may calculate a distance from the terminal 200 to the corresponding signal based on a reflected signal.

To this end, the distance measuring sensor may include, for example, a time of flight (ToF) sensor. For example, the ToF sensor may include a transmitter that emits an optical signal transformed to a specific frequency, and a receiver that receives and measures a reflected signal. When the ToF sensor is installed on the terminal 200, the transmitter and the receiver may be spaced apart from each other to avoid signal affection therebetween.

Hereinafter, the laser light signal, the IR signal, the ultrasonic signal, the carrier frequency, the impulse signal, and the UWB signal described above may collectively be referred to as ‘signal’. In this specification, ‘UWB signal’ which is rarely affected by an obstacle will be exemplarily described. Therefore, it can be said that the distance measuring sensor plays a role of calculating a distance from the terminal 200 to a point where a signal is emitted. In addition, the distance measuring sensor may include a transmitter that emits signals and one receiver or a plurality of receivers for receiving reflected signals.

Hereinafter, an exemplary configuration of the charging station 300 for charging a power supply unit (battery) included in the moving robot according to the present disclosure will be described with reference to FIG. 2D.

Referring to FIG. 2D, the charging station 300 may include a charging contact unit 320, a sensing unit 330, a communication unit 340, and a control unit (or processor).

The charging station 300 may include a charge contact unit 320 configured to transmit and receive electric signals with the moving robot 100 and to charge the battery included in the moving robot 100. When a connector provided in the moving robot 100 and the charging contact unit 320 are in contact with each other, the battery provided in the moving robot 100 may be charged.

The sensing unit 330 may sense a position, a traveling path, and a posture (a direction which the moving robot faces) of the moving robot 100 which is approaching the charging station 300.

Thereafter, the control unit (processor) may transmit information sensed by the sensing unit 330 to the moving robot 100 through the communication unit 340, so that the moving robot properly docks to the charging station (or the connector of the moving robot and the charging contact unit of the charging station are properly in contact with each other).

In addition, the sensing unit 330 may be configured to sense surrounding information of the charging station 300. For example, the sensing unit 330 may sense an event occurring in a space where the charging station 300 is installed.

The sensing unit 330 may also sense information related to the moving robot 100 or information related to the terminal 300.

For example, the sensing unit 330 may sense a distance between the moving robot 100 and the charging station 300, the position of the moving robot 100, a direction (or angle) that the moving robot 100 is located, a traveling path (or traveling trajectory) of the moving robot 100, and whether or not the moving robot 100 is approaching the charging station 300.

Also, the sensing unit 330 may sense location information (position information) regarding the terminal 200 with respect to the charging station 300.

For this, the sensing unit 330 may include a UWB module configured to transmit and receive UWB signals to and from a UWB module provided in the terminal 200 or the moving robot 100.

That is, the sensing unit 330 may include a distance measuring sensor.

The distance measuring sensor may emit at least one of a laser light signal, an IR signal, an ultrasonic signal, a carrier frequency, and an impulse signal, and may calculate a distance to the corresponding signal based on a reflected signal.

To this end, the distance measuring sensor may include, for example, a time of flight (ToF) sensor. For example, the ToF sensor may include a transmitter that emits an optical signal transformed to a specific frequency, and a receiver that receives and measures a reflected signal. The transmitter and the receiver may be spaced apart from each other to avoid signal affection therebetween.

The communication unit 340 may perform communication with an external server 500, the terminal 200, or the moving robot 100 through wireless communication. The communication unit 340 transmits and receives data by being equipped with a communication module such as Wi-Fi, WiBro, and the like, as well as through short-range wireless communications such as

Zigbee and Bluetooth. In addition, the communication unit 340 may include a UWB module for transmitting a UWB signal.

Also, the communication unit 340 may perform communication with the server 400, the terminal 200, or the moving robot 100 through the network communication described above. To this end, the communication unit 340 may be wirelessly connected to the mobile communication network and may communicate with the server 500, the terminal 200, or the moving robot 100 through the mobile communication network.

However, the present disclosure is not limited to this, and the communication unit 340 may be configured to directly communicate with the moving robot 100 or the terminal 200.

Hereinafter, FIG. 3 is a conceptual view illustrating a signal flow of devices for setting a boundary with respect to a moving robot, for example, a signal flow of the moving robot 100, the terminal 200, a GPS 60, the location information transmitter 50, and the charging station 300.

The signal transmitted from the charging station 300 may be an Ultra-wideband (UWB) signal. To this end, the charging station 300 may comprise at least one UWB module (UWB sensor). In this case, the moving robot 100 may receive the UWB signal transmitted from the charging station 300, and determine the current position based on the UWB signal.

In addition, the charging station 300 may include a GPS module to transmit GPS signals. In this case, the GPS signals transmitted from the charging station 300 may be received by the GPS satellite. The GPS satellite may transmit a reception result of the GPS signals received from the charging station 300 to the moving robot 100.

When the location information transmitter 50 transmits a signal by its UWB sensor, the terminal 200 may receive a signal related to location information from the location information transmitter 50 through a UWB module provided in the terminal 200 itself. At this time, a signaling method of the location information transmitter 50 and a signaling method between the moving robot 100 and the terminal 200 may be the same or different from each other.

For example, the terminal 200 may transmit ultrasonic waves and the moving robot 100 may receive the ultrasonic waves of the terminal 200 to follow the terminal 200. As another example, a marker may be attached on the terminal 200. The moving robot 100 may recognize the marker attached on the terminal 200 by capturing a moving direction of the terminal, so as to follow the terminal 200.

In FIG. 3, location information may be received from the location information transmitter 50 or the GPS 60. A GPS signal, an ultrasonic signal, an infrared signal, an electromagnetic signal, or a UWB signal may be used as a signal corresponding to the location information.

The moving robot needs to collect location information for setting a travel area and a boundary. The moving robot 100 may collect location information by setting any one point of an area as a reference location. At this time, a location of any one of an initial start point, the charging station, and the location information transmitter 50 may be set as the reference location. The moving robot 100 may generate coordinates and a map for the area on the basis of the set reference location and store the generated coordinates and map. When the map is generated and stored, the moving robot 100 may move based on the map.

In addition, the moving robot 100 may set a new reference location at every operation, and determine a location within the area based on the newly-set reference location.

Also, the moving robot 100 may receive location information collected from the terminal 200 which is moving along a predetermined path.

The terminal 200 may move arbitrarily and its moving path may change according to a subject which moves the terminal. However, in order to set a travel area of the moving robot, the terminal 200 may preferably move along an outer side of the travel area.

The terminal 200 calculates coordinates of a location within an area based on a reference location. In addition, the moving robot 100 may collect location information while moving with following the terminal 200.

When the terminal 200 or the moving robot 100 travels along a predetermined path alone, the terminal 200 or the moving robot 100 may calculate a current location based on a signal transmitted from the GPS 60 or the location information transmitter 50.

The moving robot 100 and the terminal 200 may move by setting the same reference location with respect to a predetermined area. When the reference location is changed at every operation, the reference location set with respect to the terminal 200 and location information collected from the reference location may be transmitted to the moving robot 100. The moving robot 100 may set a boundary based on the received location information.

Meanwhile, the moving robot 100 and the terminal 200 may determine their relative locations using Ultra-wide Band (UWB) technology. To this end, one of UWB modules may be a UWB anchor and the other one may be a UWB tag.

For example, the UWB module 230 of the terminal 200 may operate as ‘UWB tag’ that emits an UWB signal, and the UWB module of the moving robot 100 may operates as ‘UWB anchor’ that receives a UWB signal.

However, it should be noted that the present disclosure is not limited to this. For example, the UWB module 230 of the terminal 200 may operate as an UWB anchor, and the UWB module of the moving robot 100 may operate as a UWB tag. In addition, the UWB module may include one UWB anchor and a plurality of UWB tags.

Hereinafter, description will be given of a method in which the moving robot 100 and the terminal 200 determine (recognize) their relative locations through a UWB communication technology. First, a distance between the moving robot 100 and the terminal 200 is calculated using a distance measurement technology such as a ToF (Time of Flight) scheme.

Specifically, a first impulse signal, which is a UWB signal radiated (emitted) from the terminal 200, is transmitted to the moving robot 100. To this end, the UWB module of the terminal 200 may operate as ‘UWB tag’ for transmission and the UWB module of the moving robot 100 may operate as ‘UWB anchor’ for reception.

Here, the UWB signal (or the impulse signal) can be smoothly transmitted and received even if an obstacle exists in a specific space, and the specific space may have a radius of several tens of meters (m).

The first impulse signal may be received through the UWB anchor of the moving robot 100. The moving robot 100 which has received the first impulse signal transmits a response signal to the terminal 200. Then, the terminal 200 may transmit a second impulse signal, which is an UWB signal with respect to the response signal, to the moving robot 100. Here, the second impulse signal may include delay time information which is calculated based on a time at which the response signal has been received and a time at which the second impulse signal has been transmitted responsive to the response signal.

The control unit of the moving robot 100 may calculate a distance between the moving robot 100 and the terminal 200, based on a time at which the response signal has been transmitted, a time at which the second impulse signal has been arrived at the UWB anchor of the moving robot 100, and the delay time information included in the second impulse signal.

$\mspace{304mu} {{Distance}\text{?}c*\frac{t_{2} - t_{1} - {t\text{?}}}{2}}$ ?indicates text missing or illegible when filed

Here, t2 denotes an arrival time of the second impulse signal, t1 denotes a transmission time of the response signal, treply denotes a delay time, and c denotes a constant value indicating a speed of light.

As such, the distance between the moving robot 100 and the terminal 200 can be determined by measuring a time difference between signals transmitted and received between the UWB tag and the UWB anchor included in the moving robot 100 and the terminal 200, respectively.

A distance between the moving robot 100 and the location information transmitter 50 and a distance between the terminal 200 and the location information transmitter 50 can also be determined in the same or similar manner.

Hereinafter, an operation of setting a boundary with respect to the moving robot 100 using the location information transmitter 50 and the terminal 200 without laying wires under the ground will be described, with reference to FIGS. 4A to 4C.

In this manner, a boundary which is a reference of a travel area may be set using the location information transmitter 50, the terminal 200, and the moving robot 100, or using only the location information transmitter 50 and the moving robot 100, without embedding wires. A travel area which is distinguished by the boundary may be referred as to ‘wireless area.’

The ‘wireless area’ may be one or plural. In addition, one wireless area may include a plurality of spot areas additionally set in the corresponding area, so that a mowing function performed by the moving robot 100 can be performed more efficiently.

A boundary must be set so that the moving robot 100 can perform mowing while moving in a travel area set outdoors. Then, a travel area, namely, a wireless area in which the moving robot 100 is to travel is designated inside the set boundary.

Referring to FIG. 4A, there may be various obstacles 10 a, 10 b, and 10 c at the outdoors in addition to a house illustrated in the drawing. Here, the obstacles 10 a, 10 b, and 10 c may include, for example, fixed obstacles such as a building, a rock, a tree, a swimming pool, a pond, a statue, a garden, and the like, which exist at the outdoors, and obstacles that move. Also, size and shape of the obstacles 10 a, 10 b, and 10 c may be very various.

If the obstacles are present close to the set boundary, the boundary must be set, from the beginning, to avoid these various obstacles 10 a, 10 b, 10 c.

However, as illustrated in FIG. 4A, when the obstacles 10 a, 10 b, and 10 c exist within a travel area set based on a boundary R, additional boundaries for the respective obstacles 10 a, 10 b, and 10 c should be set or the previously-set boundary should be changed through the same or similar process to the method of setting the travel area inside the boundary R.

Also, in the present disclosure, a plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be installed in advance in a predetermined area, in order to set a boundary without laying wires.

The plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may transmit signals. Specifically, the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may transmit signals to one another or may transmit signals to the moving robot 100 and/or the terminal 200.

Here, the signals may include, for example, UWB signals, ultrasonic signals, infrared signals, Bluetooth signals, Zigbee signals, or the like.

At least three of the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be installed in a spaced manner. Also, the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be installed at high points higher than a reference height, in order to minimize signal interference when the UWB sensor is not included.

The plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 is preferably installed at locations adjacent to a boundary to be set. The plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be installed outside or inside a boundary to be set.

For example, FIG. 4A illustrates a plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 installed inside the boundary R, but the present disclosure is not limited thereto. For example, the plurality of location information transmitters 50M, 51, 52, 53, 54 and 55 may be installed outside the boundary R, or some may be installed inside the boundary R and the others outside the boundary R.

When the location information transmitter 50M, 51, 52, 53, 54, 55 includes a UWB sensor, the UWB sensor may transmit and receive UWB signals to and from the moving robot 100 and/or the terminal 200 located in a predetermined area, so as to calculate location information regarding the moving robot 100 and/or the terminal 200.

For example, the moving robot 100 may calculate the location of the moving robot 100 by comparing amounts/intensities of signals of the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 and determining a spaced distance and direction from each location information transmitter. A method of calculating location information regarding the terminal 200 may be similarly performed.

At least one of the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be a reference location information transmitter 50M for setting a boundary. The reference location information transmitter 50M may be installed at a place where a charging station 70 is located, for example, as illustrated in FIG. 4A.

coordinates values of the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may be set based on the reference location information transmitter 50M. More specifically, the location information transmitter 50M may transmit and receive signals to and from the remaining location information transmitters 51, 52, 53, 54, and 55, to calculate x and y coordinate values corresponding to the locations of the remaining location information transmitters, with respect to the reference location information transmitter as a zero point. Accordingly, the location information regarding the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 can be set.

When the moving robot 100 sets the charging station 70 where the reference location information transmitter 50M is located as an operation start point, it may be easier to determine (recognize) the location of the moving robot 100 at every operation. Also, when a battery gauge is insufficient during the travel of the moving robot 100, the moving robot 100 may move to the reference location information transmitter 50M where the charging station 70 is located and charge the battery.

When the reference location information transmitter 50M is installed at a place where the charging station 70 is located, it is not necessary to set the location of the charging station 70 separately.

On the other hand, when the moving robot 100 becomes significantly far away from the reference location information transmitter 50M as it keeps traveling, the reference location information transmitter may be changed to another location information transmitter which is located close to a current location of the moving robot, based on amounts/intensities of signals transmitted from the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55.

On the other hand, unlike FIG. 4A, when the charging station 70 is located outside the boundary R, that is, the boundary has been set at an inner side than the charging station 70, the moving robot 100 may return to the charging station over the boundary for recharging the battery.

However, when the charging station 70 is located outside the boundary, a moving area (not shown) may be additionally set between the charging station 70 and the travel area set within the boundary, so as to guide the moving robot 100 to return to the charging station 70 located outside the boundary.

Hereinafter, FIG. 4B exemplarily illustrates a method of setting a boundary for the moving robot 100 and a travel area with respect to the boundary, by using the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 and the terminal 200.

First, the terminal 200 moves from the location information transmitter 55 along a first path 401 at an outer side of an area, in which lawn is planted. At this time, the terminal 200 may be moved by a person, but may also be moved by another transportation device such as a drone.

The terminal 200 may determine a current location through the location information transmitter 55 or a GPS. As the mobile terminal 200 moves, a distance and direction to each location information transmitter may be calculated based on signals transmitted from the other location information transmitters 51 to 54. Accordingly, coordinates of the plurality of points corresponding to the change of the location of the terminal 200 may be recognized and stored as location information.

In this regard, each of the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 may transmit a UWB including unique information for identifying a signal. Accordingly, the terminal 200 can individually analyze and process a first signal 411 transmitted from the first location information transmitter 51, a second signal 412 transmitted from the second location information transmitter 52, a third signal 413 transmitted from the third location information transmitter 53, and a fourth signal 414 transmitted from the fourth location information transmitter 54.

In addition to this, the first to third location information transmitters 51 to 53 may transmit and receive signals 421 to 423 to the fourth location information transmitter 54, which is located close to the current location of the terminal 200, receive a response signal to the transmitted signals, and transmit a signal 424 corresponding to the response signal to the terminal. The terminal can check whether or not there is an error between the current location of the corresponding location information transmitter 54 and the predefined location (initially-installed point) based on the signal 424.

According to this, the location error of the location information transmitter can be checked together when the moving robot 100 moves for setting the travel area or the wireless area.

When the movement corresponding to the first path 401 is completed, for example, when the first path 401 forms a shape of a closed curve or reaches a designated end point, the terminal 200 transmits location information, which has been stored while moving along the first path 401, to the moving robot 100.

Then, the moving robot 100 may set a line, which sequentially connects the location information stored while the terminal 200 moves along the first path 401, or an outer line of the line, as a boundary R. In addition, the moving robot 100 may set an inner area of the first path 401 with respect to the set boundary R as a travel area or a wireless area.

The moving robot 100 may perform test traveling in the set travel area or wireless area. At this time, the boundary and/or the travel area may be partially modified by the moving robot 100. For example, the boundary and/or the travel area for the moving robot 100 may be partially modified in consideration of situation information, collected when a new obstacle is detected, when an existing obstacle is removed, when an uneven surface or a pothole is detected, or when a non-travelable spot due to the traveling function of the moving robot 100 is detected.

Or, as illustrated in FIG. 4B, the moving robot 100 follows the location of the terminal 200 at a predetermined distance while the terminal 200 moves along the first path 401, and accordingly the boundary and/or the travel area for the moving robot 100 can be set without additional test traveling.

At this time, there may be a difference between the first path 401 along which the terminal 200 has moved and the moving path of the moving robot 100 following the terminal 200. That is, the moving robot 100 can move, following the terminal 200, in a manner of ignoring or removing a location which the moving robot 100 cannot follow on the track of the first path 401, along which the terminal 200 has moved. In this case, the moving robot 100 may store the corresponding location change and may keep following the current location of the terminal 200 based on points corresponding to the location change.

When the distance between the terminal 200 and the moving robot 100 exceeds a predetermined distance as the traveling speed of the moving robot 100 is slowed due to obstacle avoidance or the like, a designated warning sound (‘first warning sound’) may be output from the moving robot 100 to notify the excess so that a user or the like moving the terminal 200 can stop the movement of the terminal 200.

Thereafter, when the moving robot 100 restarts to travel by avoiding obstacles and the like in a designated manner and accordingly the distance to the terminal 200 in the stopped state is reduced to be in a designated range again, a corresponding warning sound (‘second warning sound’) may be output from the moving robot 100 to notify it so that the user or the like moving the terminal 200 can perform the movement.

Meanwhile, FIG. 4B exemplarily illustrates that the location information regarding the moving robot 100 and/or the terminal 200 is calculated by the plurality of location information transmitters 50M, 51, 52, 53, 54, and 55 upon movement for setting the travel area or wireless area, but such location information may, of course, be calculated through GPS.

FIG. 4C exemplarily illustrates that additional boundaries for a plurality of obstacles 10 a, 10 b, and 10 c existing in a travel area (or wireless area) 410 in a state where a boundary R and the travel area inside the boundary R have been set.

In FIG. 4C, if there are obstacles 10 a, 10 b, and 10 c having a predetermined size or greater inside the set travel area 410, additional boundaries for the detected obstacles 10 a, 10 b, and 10 c may be set.

The moving robot 100 (or the terminal 200 and the moving robot 100 or the terminal 200) may set additional boundaries and a travel area with respect to the additional boundaries by moving along outer peripheries of the obstacles 10 a, 10 b, and 10 c in the same or similar manner as described above with reference to FIG. 4B.

In FIG. 4C, dashed lines formed at the outside of the obstacles 10 a, 10 b, 10 c may indicate the additional boundaries. Unlike the boundary set in FIG. 4B, an inner side is set as a non-travelable area and an outer side as a travelable area, with respect to the set additional boundary.

Thus, the change of the travel area due to the setting of the additional boundary can be reflected in the modification of the existing boundary and travel area. A map corresponding to the existing boundary and travel area can also be modified accordingly.

The moving robot 100 may perform operations such as weeding and the like while moving in the travelable area within the travel area. While the moving robot 100 moves in the travelable area within the travel area, the plurality of location information transmitters 50M, 51, 52, 53, 54 and 55 transmit signals, for example, UWB signals {circle around (1)} to one another, thereby determining their locations. Also, the plurality of location information transmitters 50M, 51, 52, 53, 54 and 55 transmit signals, for example, UWB signals {circle around (2)} to the moving robot 100, so that the moving robot 100 can recognize its current location within the travel area.

Meanwhile, the moving robot 100 according to the present disclosure may determine (recognize) the relative location of a location information transmitter or a charging station based on a UWB signal transmitted from the location information transmitter or the charging station.

Here, the location information transmitter or the charging station that transmits the UWB signal may be referred to as “UWB tag”. The moving robot 100 that recognizes the position by receiving the UWB signal transmitted from the location information transmitter or the charging station may be referred to as “UWB anchor”. An Angle of Arrival (AoA) positioning technology may be used as one of positioning technologies by which a UWB anchor recognizes the position of a UWB tag.

The moving robot 100 uses the AoA (Angle of Arrival) positioning technique to determine the relative location of the location information transmitter. Hereinafter, an AoA (Angle of Arrival) positioning technique will be described with reference to FIG. 5A.

Referring to FIG. 5A, the UWB anchor includes antennas A1 and A2 in a first transceiver and a second transceiver, respectively, for receiving UWB signals. The UWB tag T1 transmits the UWB signals through an antenna of a third transceiver (Transmit Signal). Then, the first antenna A1 and the second antenna A2 of the UWB anchor receive the UWB signals.

At this time, if a distance I between the UWB anchor and the UWB tag T1 is longer than a spaced distance d between the first antenna A1 and the second antenna A2 provided in the UWB anchor, an incident shape as shown in FIG. 5A is shown if the transmitted UWB signals are in the form of a plane wave.

Therefore, a distance difference is caused between the UWB signals incident on the first antenna A1 and the second antenna A2. The distance difference corresponds to p in FIG. 5A. An angle formed by a first line connecting the first antenna A1 and the second antenna A2 and a second line orthogonal to the first line is θ. Therefore, the angle θ may be calculated through the following Equation 1.

$\begin{matrix} {p = {d\; \sin \; \theta}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\ {{\sin \; \theta} = \frac{p}{d}} & \; \end{matrix}$

Meanwhile, the distance between the first antenna A1 or the second antenna A2 and the UWB tag T1 may be measured using two-way ranging. Two-way ranging is a method in which a transmitter and a receiver share their own time information while exchanging signals several times so as to eliminate a time error and thus measure a distance.

When the spaced distance 1 between the first antenna A1 or the second antenna A2 and the UWB tag T1 is known and the angle θ described above is obtained, a relative location of the UWB tag T1 with respect to the first antenna A1 and the second antenna A2 may be determined through the following Equation 2.

$\begin{matrix} {\frac{\alpha}{2\pi} = \frac{p}{\lambda}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \\ {\theta = {\sin^{- 1}\frac{\alpha \; \lambda}{2\pi \; d}}} & \; \end{matrix}$

Here, α denotes a phase difference between UWB signals received by the first transceiver and the second transceiver provided in the UWB anchor.

As described above, the UWB anchor may transmit and receive signals to and from the UWB tag, thereby determining the relative position of the UWB tag.

Referring to FIG. 6A, the charging station 300 for charging the moving robot 100 may be installed within the boundary R of the aforementioned wireless area. The charging station 300 may also include a communication unit 340 to transmit signals, for example, UWB signals, indicating a location.

When it is determined that the moving robot 100 located within the area is required to be recharged, the moving robot 100 should determine a relative position by transmitting and receiving signals, for example, UWB signals, to and from the charging station 300, in order to approach a point (or position) where the charging station is installed. More specifically, the moving robot 100 should recognize distance information d from its current position to the charging station 300 and angle information θ formed by its current position and the charging contact unit of the charging station.

On the other hand, if the moving robot 100 approaches the charging station 300 without a plan, it is difficult to expect that the charging connector located on the front of the moving robot 100 is accurately connected to the charging contact unit of the charging station 300. Therefore, it is necessary to set a planned docking path in consideration of accurate connection, i.e., docking.

In the case where the boundary of the area is set by wires, the moving robot can approach the charging station along the wires of the boundary. However, when the boundary of the area is set using the wires, various problems occur in view of costs, management, re-installation and the like.

Thus, as illustrated in FIGS. 6B and 6C, it may be considered that a guide wire with a predetermined length may be buried near the charging station.

A docking method using a guide wire 610 will be described in detail as follows. First, the moving robot 100 rotates (R) its head by recognizing a heading direction P1 toward the charging station 300 at its current position based on a magnetic value of a geomagnetic sensor (compass sensor) and signals transmitted from signal transmission modules 341 and 342 of the charging station 300.

A distance I from the current position of the moving robot 100 to the charging station 300 may be recognized based on the signals transmitted from the signal transmission modules 341 and 342. At this time, an angle θ of a point where a line connecting the distance 1 and a line orthogonal to an installed position of the charging station 300 may be calculated.

Subsequently, as illustrated in FIG. 6C, the moving robot 100 is controlled to move to a point spaced apart from the charging station 300 by a distance d, for example, to a point spaced by 2 m from the charging station 300, considering the installation of the guide wire connected to the charging station 300.

However, the docking method requires for laying the guide wire and has a coverage up to only 180 degrees with respect to the installed position of the charging station 300. This causes a problem when the moving robot 100 attempts docking in a signal blind spot. In addition, a magnetic field SLAM or the like must be utilized for accurate docking.

Accordingly, the present disclosure has implemented a moving robot, capable of setting a docking path without having to install a wire along a boundary or laying a guide wire under the ground around a charging station, and a method of controlling the same. The present disclosure also has implemented a moving robot, capable of performing accurate docking with covering all the 360-degree directions and without using a magnetic field SLAM, and a method of controlling the same.

Hereinafter, a method of controlling a moving robot according to an embodiment of the present disclosure will be described in detail with reference to FIGS. 7, 8A, 8B, 8C, 8D, 8E and 8F. The moving robot 100 according to the present disclosure is implemented to travel in one area where a charging station is installed, and the travel area of the moving robot may be replaced with the aforementioned wireless area.

In FIG. 7, coordinates information regarding a point, to which the moving robot 100 has moved by a reference distance from the charging station 300, in a state where the main body of the moving robot 100 is in contact with the charging station 300 (S10).

Specifically, in a state where a charging connector of the moving robot 100 is in contact with a charging contact unit of the charging station 300, the moving robot 100 moves backward by a predetermined distance r1. At this time, the predetermined distance r1 may be referred to as a reference distance, and may be a length (about 30 cm) as long as a radius of the main body of the moving robot. Then, the moving robot 100 moves backward to a point which is spaced apart from the charging station by the reference distance, stops at the point, and then stores coordinates information regarding the point.

For this purpose, the moving robot 100 may transmit and receive signals (e.g., UWB signals) to and from the charging station 300 from when the main body is released from the charging contact unit of the charging station 300, check in real time a point to which it moves, and determine coordinates information regarding the corresponding point (hereinafter, referred to as ‘return reference point’).

Specifically, two UWB modules (or UWB sensors) provided in the main body of the moving robot receive UWB signals (hereinafter, referred to as ‘first signal’) transmitted from the charging station 300, respectively. In addition, two UWB modules (or UWB sensors) provided in the charging station 300 receive UWB signals (hereinafter, referred to as ‘second signal’) transmitted from the moving robot 100, respectively. The charging station 300 and the moving robot 100 each may include a plurality of antennas electrically connected to the UWB modules.

The plurality of UWB modules provided in the moving robot 100 may be disposed symmetrically in right and left directions with respect to the front of the moving robot main body, and each may receive the first signal from the charging station 300 so as to determine the position of the charging station based on the current position of the main body.

At this time, the UWB modules of the moving robot 100 and the charging station 300 may be electrically connected with a plurality of antennas. In this case, it may be immediately determined whether the charging station 300 is located at the front or at the rear with respect to a head direction of the main body of the moving robot 100. As a result, a rotating direction of the head to be described later can be easily determined.

In one embodiment, coordinates information regarding the point to which the main body of the moving robot 100 has moved backward by the reference distance r1 in the state of being in contact with the charging station 300, namely, ‘return reference point’ may include angle information calculated based on the second signal.

Referring to FIG. 8A, the moving robot 100 located at the return reference point includes a plurality of UWB modules (or UWB sensors) 111 and 112 for transmitting and receiving UWB signals to and from the charging station 300. The plurality of UWB modules (or UWB sensors) 111 and 112 of the moving robot may be disposed on the front of the head of the moving robot in a spaced manner in right and left directions. However, those components may not be limited to the arrangement.

As illustrated in FIG. 8A, the charging station 300 facing the moving robot also includes a plurality of UWB modules (or UWB sensors) 341 and 342 for transmitting and receiving UWB signals to and from the moving robot 100.

The UWB signals transmitted from the first UWB module 111 of the moving robot 100 are received by the antennas of the first UWB module 341 and the second UWB module 342 of the charging station 300. The UWB signals transmitted from the first UWB module 341 of the charging station 300 are received by the antennas of the first UWB module 111 and the second UWB module 112 of the moving robot 100.

Accordingly, the control unit of the moving robot 100 may acquire first angle information θ2 formed by the first UWB module 111 of the moving robot 100 and the first UWB module 341 and the second UWB module 342 of the charging station 300. The control unit of the moving robot 100 may acquire second angle information θ3 formed by the second UWB module 112 of the moving robot 100 and the first UWB module 341 and the second UWB module 342 of the charging station 300.

At this time, since the moving robot 100 which has been in contact with the charging station 300 is moved backward so as to be located at the return reference point, the moving robot 100 maintains a state/posture parallel to the charging station 300. Therefore, the first angle information θ2 and the second angle information θ3 become the same value. However, the same value includes a range having tolerable error/difference even if the first angle information θ2 and the second angle information θ3 are not completely equal, and is limited to a value belonging to a docking allowable range.

Along with this, the control unit of the moving robot 100 senses a value (i.e., heading value) P1 of the head direction of the moving robot 100 with respect to the magnetic north direction, at the return reference point, through a compass sensor or an IMU sensor provided in the moving robot 100. The control unit of the moving robot may acquire an angle θ1 between a heading value at the time when the main body is located at the return reference point and a heading value in the magnetic north direction. This information may be stored as third angle information.

As such, after the moving robot 100 stops at the return reference point for a predetermined time from the charging station 300, the moving robot 100 travels in one area along a designated (set) travel path.

While the main body of the moving robot 100 travels in the one area, the control unit of the moving robot may output a control command to return to the charging station 300 based on the state of the power supply unit that supplies power to the main body (S20).

Specifically, the control unit of the moving robot may output a control command to return to the charging station when a remaining battery level of the power supply unit reaches a reference range. Here, the reference range means a degree that travel and docking for returning to the charging station can be carried out by the remaining battery level of the moving robot.

Meanwhile, in one example, the control command output by the control unit of the moving robot may also be transmitted to the charging station. In this case, the charging station 300 which has received the control command may transmit to the moving robot 100 a signal for searching for the current position of the moving robot 100, a signal indicating whether the moving robot 100 can be recharged, and/or a signal for guiding the return of the moving robot 100.

Next, in response to the output of the control command, the control unit of the moving robot 100 checks the position of the charging station 300 at the current position of the moving robot 100, based on the first signal transmitted from the charging station 300 and the second signal transmitted from the main body of the moving robot 100. At the same time, the control unit of the moving robot 100 may control the moving robot 100 to travel to the position corresponding to the stored coordinates information, namely, the return reference point (S30).

In detail, referring to FIG. 8B, when the control command to return to the charging station 300 is output during traveling in the one area, the moving robot 100 may transmit a signal (i.e., ‘first signal’) to the charging station 300 through the first UWB module 111 and the second UWB module 112. The charging station 300 may also transmit a signal (i.e., ‘second signal’) to the moving robot 100 through the first UWB module 341 and the second UWB module 342.

As for the moving robot 100, since the position of the charging station 300 is determined based on the first signal and the second signal, it can be said that the moving robot 100 operates as a UWB anchor and the charging station 300 operates as a UWB tag. Also, as for the charging station 300, since the position of the moving robot 100 is determined based on the first signal and the second signal, it can be said that the moving robot 100 operates on a UWB tag and the charging station 300 operates as a UWB anchor.

In this manner, since the moving robot 100 and the charging station 300 can determine their relative positions, the moving robot 100 can rotate the head from its current position toward the point where the charging station is located (P2).

Specifically, the control unit of the moving robot 100 may calculate distance information and angle information between the current position of the main body of the moving robot and the charging station 300 based on the first signal transmitted from the charging station 300 and the second signal transmitted through the communication unit according to the output of the control command, and control the traveling unit to rotate the head of the main body toward the point corresponding to the stored coordinates information, namely, the return reference point.

The control unit may acquire distance information 11 from the current position of the moving robot 100 to the charging station 300 after the rotation of the head of the main body.

The control unit of the moving robot may also acquire the position of the return reference point G and distance information 12 from the current position of the moving robot 100 to the return reference point G, based on an angle θ5 of a point where a signal distance between the second UWB module 112 of the moving robot 100 and the first UWB module 341 of the charging station 300 meets a virtual line connecting the return reference point and the charging station 300, and an angle θ6 of a point where a signal distance between the first UWB module 111 of the moving robot 100 and the second UWB module 342 of the charging station 300 meets the virtual line connecting the return reference point and the charging station 300.

Thereafter, as illustrated in FIG. 8C, the control unit of the moving robot 100 rotates the head toward the return reference point G, and control the main body of the moving robot 100 to move to the return reference point G.

At this time, in one embodiment, the control unit of the moving robot 100 may check in real time the position of the charging station 300 and the distance 11 from the current position of the moving robot 100 to the charging station 300, while moving to the return reference point G. At the same time, the control unit may control the moving robot to travel while checking even the distance 12 from the current position of the moving robot 100 to the return reference point G in real time.

Also, although not shown, when the distance I1 up to the charging station 300 is reduced to be within the reference range, that is, when the moving robot 100 approaches the charging station 300, an LED blinking signal or the like may be output to the charging station 300 and a signal corresponding to this may be transmitted to the moving robot 100.

As such, since the moving robot 100 can search for the return reference point G and move with respect to the searched point, instead of performing a return movement with respect to the position of the charging station, it may be similarly applied even to the case where the moving robot 100 approaches the charging station from the rear of the charging station, unlike the example illustrated in FIGS. 8A to 8C.

FIG. 8D illustrates an example in which the moving robot 100 confirms the position of the charging station 300 in real time while moving toward the return reference point G.

Specifically, while the main body of the moving robot is moving to the position corresponding to the stored coordinates information, namely, the return reference point, the control unit of the moving robot 100 determines an intersection C2 close to the head direction of the moving robot main body as the position of the charging station 300, of two intersections Cl and C2 between a first circle that a distance between the first UWB anchor provided in the communication unit and the first UWB tag 341 of the charging station 300 is a radius and the first UWB anchor is a center, and a second circle that a distance between the second UWB anchor provided in the communication unit and the second UWB tag 342 of the charging station 300 is a radius and the second UWB anchor is a center.

Also, in order for the moving robot 100 to accurately reach the return reference point, the control unit may control the main body of the moving robot 100 to travel while modifying (correcting) the head direction of the main body, using the position of the charging station 300, angle information, for example, angles θ1, θ2, θ3, included in the stored coordinates information, and angle information θ5, θ6 acquired after rotating the head direction toward the charging station. This modification (or correction) may be performed at a time point when the moving robot 100 reaches or approaches a virtual circle 820 with a radius corresponding to the distance from the current position of the moving robot 100 to the charging station 300.

When the main body reaches the return reference point, the control unit of the moving robot 100 calculates a rotation angle for docking to the charging station 300, based on the first signal transmitted from the charging station 300 and the second signal transmitted by the main body of the moving robot 100.

Specifically, the control unit determines the head direction of the moving robot main body, based on the first signal transmitted from the charging station 300 and the second signal transmitted by the communication unit, after the moving robot main body moves to the position corresponding to the stored coordinates information. The control unit then controls the traveling unit so that the head rotates according to the determined head direction.

Referring to FIG. 8E, when the moving robot 100 reaches the return reference point, the control unit may acquire an angle θ8 of the head direction to be rotated from a current heading value for docking, based on a heading value θ1 with respect to the magnetic north direction measured through the compass sensor at the time of storing the coordinates information, and a current heading value θ7 relative to the magnetic north direction.

In the present disclosure, it may also be possible to calculate the angle θ8 of the head direction to be rotated from the current heading value without using the compass sensor.

In detail, when the head direction of the moving robot 100 does not coincide with the docking direction, a difference occurs in signal reception distances of UWB signals which are received by the antennas of the first UWB module 111 of the moving robot 100 from the first and second UWB modules 341 and 342 of the charging station 300 and signal reception distances of UWB signals which are received by the antennas of the second UWB module 112 of the moving robot 100 from the first and second UWB modules 341 and 342 of the charging station 300. This difference in the signal reception distances causes an angle difference at a point where a virtual line indicating the same signal reception distance meets a line according to a current arrangement direction of the first and second UWB modules 111 and 112 of the moving robot 100. The angle difference is an angle value θ8 by which the another UWB module 112 is to be rotated with respect to the one UWB module 111 (a UWB module/antenna with a shorter signal reception distance).

Also, in one embodiment, even after the head of the moving robot 100 located at the return reference point is rotated according to the determined head direction, the control unit may determine whether or not to correct or modify the determined head direction, based on a difference between distances at which the first signal transmitted from the charging station 300 is received in the first and second UWB modules 111 and 112 of the moving robot 100, respectively.

Specifically, after the head of the moving robot is rotated according to the determined head direction, when a signal distance of the UWB signal received by the antenna of the first UWB module 111 of the moving robot and a signal distance of the UWB signal received by the antenna of the second UWB module 112 of the moving robot are different from each other, the head is rotated to modify the heading value by an angle corresponding to the difference. When it is determined that the two signal reception distances are not different from each other (or if the difference is ignorable), it is determined that an additional modification is not carried out.

For example, referring to FIG. 8F, when the determined head direction is a correct docking direction, the control unit determines that the angle information θ1, θ2 included in the stored coordinates information and the angle values calculated based on the first signal and the second signal with respect to the current head direction have no difference, and controls the moving robot 100 to go straight toward the charging station 300 by a distance r1.

At this time, although not shown, in one embodiment, even the charging station 300 may receive the signals transmitted from the moving robot 100 through the antennas of the plurality of UWB modules, and then transmit a docking initiation signal to the moving robot 100 when there is no difference between signal reception distances.

On the other hand, the moving robot may temporarily deviate from the return reference point upon modifying the determined head direction. That is, before correcting the head direction of the moving robot 100, backward/forward/leftward/rightward travel by a predetermined distance from the current position may be performed. In this case, the control unit may control the moving robot 100 to move from a changed position to the return reference point again.

As such, when it is determined that the reception distance of the first signal transmitted from the charging station 300 and received by the first UWB module 111 of the moving robot 100 is the same as the reception distance of the first signal received by the second UWB module 112, the current head direction is determined as a docking direction. Accordingly, the moving robot 100 moves straightly until the charging connector of the moving robot 100 is connected to the charging contact unit of the charging station 300.

Then, the control unit rotates the head of the moving robot according to the calculated rotation angle, and then performs docking to the charging station 300 (S40).

When the charging of the battery is completed after the docking, the control unit controls the moving robot to return to the position where the moving robot has been located when the control command is output. To this end, the control unit may store position information of the moving robot main body at the time point when the control command is output, and control the traveling unit so that the main body moves to the stored position information.

As described above, according to the present disclosure, the moving robot can return to the charging station even if it is located at anywhere in all the 360-degree directions with reference to the charging station, by using a plurality of UWB modules (or UWB sensors) provided in the moving robot and a plurality of UWB modules provided in the charging station.

As such, the moving robot can return to the charging station even if it is located at anywhere in all the 360-degree directions with respect to the charging station, thereby minimizing a UWB signal blind spot.

In detail, referring to FIG. 9, there is a case where the moving robot 100 comes close for docking from the rear side with respect to the charging contact unit of the charging station 300 along the travel path of the moving robot 100, depending on the terrain of the area where the charging station 300 is installed. At this time, the return reference point G is not located between the moving robot 100 and the charging station 300, and is blocked by the charging station. If a guide wire is not installed, points BP1 and BP shown correspond to signal blind spots.

Setting a docking path at these points BP1 and BP2 may be realized in two ways.

One is that the moving robot 100 sets a docking path in a manner of moving along a virtual circle 920 having a radius corresponding to a distance from the charging station 300 to the moving robot 100, while recognizing its current position and the position of the charging station 300 in real time based on the first signal and the second signal transmitted and received through the plurality of UWB modules. At this time, since the return reference point G should be included in the virtual circle 920, the distance should be at least equal to or longer than a distance, namely, r1 from the charging station 300 to the return reference point G.

The other is to accurately determine coordinates of the return reference point based on the first signal and the second signal, and then to set a docking path in a manner that the moving robot moves directly toward the coordinates. In this way, while moving to the point G corresponding to the stored coordinates information, the position of the charging station can be determined in real time based on the first signal and the second signal. Also, when the position of the charging station is included in a path along which the moving robot main body moves to the stored coordinates information, the docking path may be reset by avoiding the charging station 300.

As described above, in a moving robot and a control method thereof in accordance with an embodiment of the present disclosure, a docking path for charging can be set without having to set wires in a boundary along which the moving robot travels or to lay a guide wire under the ground around a charging station. In addition, since the moving robot can cover all the 360-degree directions when docking to the charging station even if it is located at anywhere within a boundary, a signal blind spot can be minimized and accurate docking can be carried out without using a magnetic field SLAM.

The present disclosure described above can be implemented as computer-readable codes on a program-recorded medium. The computer-readable medium may include all types of recording devices each storing data readable by a computer system. Examples of the computer-readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device and the like, and may also be implemented in the form of a carrier wave (e.g., transmission over the Internet). In addition, the computer may also include the control unit 1800 of the moving robot. The above detailed description should not be limitedly construed in all aspects and should be considered as illustrative. The scope of the present disclosure should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present disclosure are included in the scope of the present disclosure. 

What is claimed is:
 1. A moving robot that travels within one area where a charging station is installed, the moving robot comprising: a traveling unit to rotate or move a main body; a power supply unit to supply power to the main body; a communication unit to transmit and receive signals to and from the charging station; a memory to store therein coordinates information regarding a point to which the main body has moved by a reference distance in a state of being in contact with the charging station; and a control unit to output a control command to return to the charging station based on a state of the power supply unit while the main body travels in the one area, wherein the control unit determines a position of the charging station from a current position of the main body based on a first signal transmitted from the charging station and a second signal transmitted by the communication unit, in response to the output of the control command, and controls the traveling unit so that the main body moves to a position corresponding to the stored coordinates information, and wherein the control unit calculates a rotation angle for docking to the charging station based on the first signal and the second signal when the main body reaches the position corresponding to the stored coordinates information, and controls the traveling unit so that a head of the main body is rotated according to the calculated rotation angle.
 2. The moving robot of claim 1, wherein the charging station is provided with a pair of Ultra-wideband (UWB) modules to transmit the first signal and receive the second signal, and wherein the communication unit of the main body is provided with a pair of UWB modules to receive the first signal and transmit the second signal.
 3. The moving robot of claim 2, wherein the pair of UWB modules provided in the communication unit is disposed to be symmetric in right and left directions with respect to the front of the main body, and determines the position of the charging station with respect to the current position of the main body by receiving the first signal from the charging station, respectively.
 4. The moving robot of claim 3, wherein the control unit, while the main body moves to the position corresponding to the stored coordinates information, determines one intersection close to a head direction of the main body as the position of the charging station, of two intersections between a first circle that a distance between a first UWB anchor provided in the communication unit and a first UWB tag of the charging station is a radius and the first UWB anchor is a center, and a second circle that a distance between a second UWB anchor provided in the communication unit and a second UWB tag of the charging station is a radius and the second UWB anchor is a center.
 5. The moving robot of claim 1, wherein coordinates information of a point to which the main body has moved backward by a reference distance in a state of being in contact with the charging station includes angle information calculated based on the first signal and the second signal.
 6. The moving robot of claim 1, wherein the control unit calculates distance information and angle information between the current position of the main body and the charging station based on the first signal received from the charging station and the second signal transmitted by the communication unit, in response to the output of the control command, and controls the traveling unit so that the head of the main body is rotated toward the position corresponding to the stored coordinates information.
 7. The moving robot of claim 6, wherein the control unit checks the position of the charging station in real time based on the first signal received through a plurality of UWB modules while the main body moves to the position corresponding to the stored coordinates information after the head of the main body is rotated toward the point corresponding to the stored coordinates information.
 8. The moving robot of claim 7, wherein the control unit, after the main body moves to the position corresponding to the stored coordinates information, determines a head direction of the main body on the basis of the angle information calculated based on the first signal received from the charging station and the second signal transmitted by the communication unit, and then controls the traveling unit so that the head is rotated according to the determined head direction.
 9. The moving robot of claim 8, wherein the control unit, after the head is rotated according to the determined head direction, checks whether or not to correct the determined head direction, based on a difference between distances at which the first signal transmitted from the charging station is received by a first UWB module and a second UWB module disposed in the main body, respectively.
 10. The moving robot of claim 9, wherein a current head direction is determined as a docking direction when it is determined that the distance at which the first signal is received by the first UWB module is the same as the distance at which the first signal is received by the second UWB module.
 11. The moving robot of claim 1, wherein the control unit controls the traveling unit so that the main body docks to the charging station by moving straightly by the reference distance, after the main body rotates the head according to the calculated rotation angle at the position corresponding to the stored coordinates information.
 12. The moving robot of claim 1, wherein the control unit determines the position of the charging station in real time based on the first signal and the second signal while the main body moves to the position corresponding to the stored coordinates information, and sets a docking path by avoiding the charging station when the position of the charging station is included in a path along which the main body moves to the stored coordinates information.
 13. The moving robot of claim 1, wherein the control unit stores position information regarding the main body at a time point when the control command has been output, and controls the traveling unit so that the main body moves to the stored position information when the main body docks to the charging station and charging of the power supply unit is completed.
 14. A method for controlling a moving robot that travels within one area where a charging station is installed, the method comprising: storing in advance coordinates information regarding a point, to which a main body of the moving robot has moved by a reference distance in a state of being in contact with the charging station; outputting a control command to return to the charging station based on a state of a power supply unit that supplies power to the main body while the main body travels in the one area; determining a position of the charging station with respect to the main body based on a first signal transmitted from the charging station and a second signal transmitted by the main body, in response to the output of the control command, and controlling the main body to move to a position corresponding to the stored coordinates information; and calculating a rotation angle for docking to the charging station based on the first signal and the second signal when the main body reaches the position corresponding to the stored coordinates information, and controlling a head of the main body to be rotated according to the calculated rotation angle.
 15. The method of claim 14, wherein the controlling the main body to move to the position corresponding to the stored coordinates information comprises: calculating distance information and angle information between a current position of the main body and the charging station based on the first signal received from the charging station and the second signal transmitted by the main body, in response to the output of the control command; and controlling the head of the main body to be rotated toward the position corresponding to the stored coordinates information.
 16. The method of claim 15, further comprising: checking the position of the charging station in real time based on the first signal received through a plurality of UWB modules provided in the main body while the main body moves to the position corresponding to the stored coordinates information after the head of the main body is rotated toward the position corresponding to the stored coordinates information.
 17. The method of claim 16, further comprising, after the main body moves to the position corresponding to the stored coordinates information: determining a head direction of the main body on the basis of the angle information calculated based on the first signal received from the charging station and the second signal transmitted by the main body; and rotating the head according to the determined head direction and docking to the charging station. 